Not applicable
The present invention generally relates to the field of aquatic floatation and transportation systems. More particularly, the invention relates to a foot-wearable human floatation apparatus used primarily for water-walking or water-skating, and a propulsion mechanism therefor.
Walking on water, like flying, has been considered an interesting mode of transportation for centuries, if not millennia. Prior attempts at creating a foot-worn floatation/propulsion system have yet to produce a water-walking apparatus that enables a human to take near-normal walking steps with confidence.
The act of walking, on land or on water, can be broken down into a sequence of coordinated basic movement pairs (each pair comprising a left leg movement and a right leg movement). There are four basic movements: Forward, an actual forward movement of the first leg and foot; Backwards, the backwards push against the resistance of the ground during which the second foot does not actually move; Up, the lifting the first leg off the ground or un-weighting of the leg during skating; and Down, applying one""s weight on the first leg. The act of walking naturally requires the smooth transition from one action to the next, and from one leg to the next. Any water-walking apparatus should allow for all four movements in the normal sequence and with the natural timing a human has learned when walking on land. A key consideration in walking on any medium is to emulate the assumed xe2x80x9c100%xe2x80x9d friction typically found when applying the Backwards movement on land. Humans slip and fall when friction is reduced during that portion of the walking cycle. In addition, a water-walking apparatus should allow a user to xe2x80x9cstep aroundxe2x80x9d a turn as a way to change directions while providing the user a feeling of stability at least somewhat similar to the stability found on solid ground. Thus, a successful water-walking apparatus should limit pitch, roll, and side-to-side motions transmitted from the float to the user without constraining the natural walking up-down, front-back, and yawing motions transmitted from the user to the float.
Skating is different than walking in several ways. Skating is a series of movements optimized for low foot-to-support medium friction situations (ice, roller blades, water), where sliding a foot across the support medium will not completely halt forward progress. Because of the low friction, the Up movement doesn""t necessarily imply lifting the foot xe2x80x94a simple easing of the pressure to reduce the (normal force generated) frictional resistance, as in Nordic skiing, is often adequate. Second, skating typically involves a gliding movement; weight is carried on the forward leg while the back leg xe2x80x9cpushes offxe2x80x9d. The person using a skating apparatus lifts the foot that has just finished the Backwards, power movement and lets himself be carried forward by momentum, weight on the forward leg. Depending on the desired speed, the user either continues the one leg glide, brings the rearward foot parallel with the gliding foot and performs a two footed glide, or brings the rearward foot to the forward position in anticipation of the next pushing movement. Note that the skater can alternate the roles of the left and right legs (the normal skating action) or repeatedly use only one leg as the pushing leg (as in powering a scooter).
A typical prior water walking apparatus comprises two elongated floats and some sort of variable resistance propulsion mechanism, typically comprising a multitude of either small rotatable flaps or fixed, rearward facing cups, pouches, or scoops. The typical prior float is generally flat bottomed and straight sided and the typical prior propulsion mechanism does not provide maximum resistance against the water at the point in the walking cycle when it is needed; specifically, the maximum resistance is needed at the beginning of the Backwards (power) movement. Prior propulsion systems either require the user to wait to take each step or allow backwards slippage. For example, U.S. Pat. No. 4,698,039 teaches an apparatus having a pair of symmetric floats, these floats being generally rectangular in cross-section and having a flat bottom over most of their length. Additionally, the ""039 patent teaches the use of a series of rotatable flaps with vertical axes spaced along either side of a central keel. The flaps move into their high resistance position only by the rearward slippage at the beginning of each step. Further, each flap is xe2x80x9cshadowedxe2x80x9d by the flap next in line, greatly reducing their propulsive power. Another attempt to provide a propulsion system with rotatable flaps with vertical axes is described in U.S. Pat. Nos. 4,261,069 and 4,117,562, both by Schaumann. In the ""069 patent there are two flaps in series in a tunnel like chamber, completely obviating the functionality of the front flap for pushing backwards against the water. The overall float shape in both these patents is again generally an elongated rectangle. The ""069 patent is notable in use of a resilient stop that both prevents the flap from opening beyond the desired point and provides a small push back toward the closed condition. However, the resilient stop only provides an initial push, the energy of which is quickly absorbed by the resistance of the water. Two examples of xe2x80x9chorizontalxe2x80x9d (viz., having a horizontal axis) flaps or pouches are provided by U.S. Pat. Nos. 5,593,334 and 5,697,822. Again, the linear series of small pouches or flaps are too small to be effective and are self-obviating because of shadowing, and again the float shape is generally conducive to instability.
Some prior devices include a tethering mechanism to keep the floats from separating. Many of these mechanisms are overly constrainingxe2x80x94that is, rather than just preventing excessive transverse separation, they instead prevent the user""s feet from moving in at least some of the degrees of freedom possible on land. Typically, the tether mechanism, if present, either inhibits a full and natural stride (i.e., the length of a step), introduces friction into what is normally a frictionless forward leg movement, prevents the redirection of a forward stride (yaw) (as is needed for turning), or inhibits the required Up and Down leg movements. For example, the ""069 patent includes an intertwined cable tether whose claimed function is explicitly to eliminate virtually all sideways motions, to limit the length of the stride, and to ensure the engagement of a tongue-and-groove mechanism for eliminating up-down motions. Another example of an overly constraining tethering mechanism is shown in U.S. Pat. No. 3,121,892 in which the two floats (actually xe2x80x9cskisxe2x80x9d in that each float is a thin, flat board similar to conventional water skis) are joined by what amounts to either a single or a double linear bearing that constrains the relative motion between the skis.
It is therefore an object of this invention to provide a water-walking apparatus in which the maximum resistance to the water is achieved at the beginning of, and maintained throughout, the Backward pushing movement. Other objectives can include providing an apparatus in which the user achieves a near land-like stability, which allows the user to transition from deep to shallow water and thence to solid surfaces (land, ice, etc.) while walking, and/or an apparatus with a foot attachment method that allows the user all normal walking motions while providing a quick release for safety. These and other objectives are met through the various embodiments discussed below.
The present invention relates to a foot-wearable apparatus for human floatation and transportation on water in a direction of travel. In one embodiment, the apparatus comprises a first buoyant float and a second buoyant float, each of said first buoyant float and said second buoyant float comprising a center of buoyancy, a bow, and a stern. Each float is defined by having a sculpted hull comprising (a) a substantially straight and generally flat inward side running from said bow to said stern, (b) a substantially convex outward side having convexity, a top edge and a bottom edge, said substantially convex outward side and said convexity running from said bow to said stern, and said convexity being away from the direction of said substantially straight inward side, said substantially convex side additionally being farther from said inward side at said top edge than at said bottom edge, and (c) a bottom side in watertight connection with said substantially straight inward side and said substantially convex outward side, said substantially straight side, said substantially convex outward side, and said bottom side forming a smooth and continuous exterior surface. Said hull is covered by a top surface. In addition, said sculpted hull comprises a foot well for housing said user""s foot and ankle, said foot well disposed through said top surface of said buoyant float and extending toward said bottom side, said foot well further located to position said user""s ankle substantially in vertical alignment with the center of buoyancy, and said foot well further comprising a bottom surface that is below said center of buoyancy. In some embodiments, said apparatus further comprises a tether having a length and connecting said first buoyant float to said second buoyant float. The substantially convex outward side and the substantially straight inward side of the hull act cooperatively to form an aerofoil whereby said sculpted hull experiences an outwardly force in use. In another embodiment, the center of buoyancy of the float is at least as high as the predicted height of said user""s ankle in said foot well. In yet another embodiment, the bottom surface of said foot well further extends to the bottom side of the hull. The foot well may also comprise a foot well cover hingedly attached to the top surface of said first or said second buoyant float, said foot well cover being adapted to hold said user""s foot in said foot well when said foot well cover is closed. In an even more preferred embodiment, the apparatus comprises a foot interface comprising a first surface connected to said foot well cover, and a second surface adapted to surround the upper surface of said user""s foot and the anterior surface of said user""s ankle in said foot well. In yet other embodiments, the bottom side further has a generally convex shape having convexity, said convexity being away from the direction of said top surface, said bottom side further comprising a flat platform extending under the bottom surface of said foot well, said platform being generally parallel to the plane of said water.
In another embodiment, the apparatus comprises a track disposed parallel to the water on said substantially straight inward side, and an attachment rider adapted for traversing said track and for accepting said tether, wherein said rider traverses said track when pulled by said tether. In yet another embodiment, the tether restricts movement between said first float and said second float in only one degree of freedom, said degree of freedom being substantially in the direction perpendicular to both the direction of travel and the vertical direction, wherein said restriction is furthermore only a limit on the maximum separation allowed in said direction. Other embodiments for tethering the two floats include a first cable comprising two ends, said two ends attached to said substantially straight inward side of said first buoyant float at two locations at the approximate predicted height of the user""s ankle in said foot well, and a second cable intertwined at least once through said first cable, said second cable further comprising two ends attached to said substantially straight inward side of said second float at two locations at the approximate predicted height of the user""s ankle in said foot well. In some embodiments, a friction reducing agent is coated on one or more of said cables. Also, the tether may be connected to a buoyant float by an adjustable attachment device, said device connecting said tether to said first float, wherein said adjustable attachment device can be used by a user to adjust the separation between said first float and said second float.
Additionally, other devices can be attached to one or both of said buoyant floats. In one embodiment, an articulation interface is attached to the stern of one float. The articulation interface is adapted for attaching a flap with a forward edge that is perpendicular to said direction of travel. In another embodiment, the buoyant float comprises an outside surface, and one or more accessory attachment interface adaptations for attaching one or more accessories are attached to said outside surface. In one embodiment, the accessory comprises one or more generally pointed protuberances adapted for increasing traction on ice in contact with said protuberances. In yet another embodiment, said accessory comprising a propulsion mechanism retraction interface located at the stern of said first buoyant float and adapted to facilitate the retractable attachment of a propulsion mechanism, which is operational when it is at least partially immersed in the water and not operational when it is substantially retracted from the water, to said float, said retraction interface comprising (a) a pivot bracket attached to said first buoyant float and adapted to pivotally connect to said propulsion mechanism, (b) a fixed anchor point attached to said first buoyant float, and (c) a retention spring adapted for connection between said propulsion mechanism and said fixed anchor point; thus, when a propulsion mechanism is attached to said pivot bracket and said retention spring, said retention spring is stressed, and said stressed retention spring generates a force on said propulsion mechanism directed to keep said propulsion mechanism at least partially immersed in water, wherein said propulsion mechanism can pivot between being at least partially immersed in water and substantially retracted from water in response to torque.
In yet another embodiment, a buoyant float may be comprised of two or more modular members shaped to fit together to form said first buoyant float.
In yet another embodiment, the invention provides a kit for producing a float for floatation and transportation on water, comprising at least two modular members sized to fit together to form a buoyant float having a center of buoyancy, a bow and a stern, said buoyant float further comprising a hull. Each hull comprises (a) a substantially straight and generally flat inward side running from said bow to said stern, (b) a substantially convex outward side having convexity, a top edge, and a bottom edge, said side and said convexity running from said bow to said stern and said convexity being away from the direction of said substantially straight inward side, said substantially convex side further being generally tilted from a top edge to a bottom edge, said top edge being generally farther from said substantially straight inward side than said bottom edge, and (c) a bottom side in watertight connection with said inward side and said outward side, said three sides forming a smooth and continuous exterior surface. Each float further comprises a top surface covering said hull and a foot well for housing said user""s foot and ankle, said foot well disposed through said top surface of said float and extending toward said bottom side, said foot well further located to position said user""s ankle substantially in vertical alignment with the center of buoyancy, and said foot well further comprising a bottom surface that is below said center of buoyancy of said float. Preferably, at least one of said one modular member comprises an attachment point for a tether at the approximate predicted height of the user""s ankle in said foot well.
In other embodiments, the invention provides a propulsion mechanism for propelling a water craft through water in a direction. Such a propulsion mechanism comprises (a) a support structure comprising a support element, said element comprising a first dimension, a second dimension, a third dimension, a first end of said first dimension and a second end of said first dimension, said first end comprising an adaptation for attachment to said water craft, and (b) a buoyant flap comprising a leading edge, a trailing edge, a width between said leading edge and trailing edge and an articulation point located within the first 25% of said width as measured from said leading edge, said buoyant flap articulated to said second end of said support element at said articulation point, said articulation having an axis of rotation that is both within 45 degrees of horizontal and substantially perpendicular to said direction of travel, said buoyant flap being movable substantially in rotation about said axis, said rotation being in a semicylindrical space behind said axis, said space being away from said direction of travel.
In another embodiment, the propulsion mechanism comprises (a) a support structure comprising a support element, said element comprising a first dimension, a second dimension, a third dimension, a first end and a second end, said first end comprising an adaptation for attachment to said water craft; (b) a flap comprising a leading edge, a trailing edge, a width between said leading edge and trailing edge and an articulation point located within the first 25% of said width as measured from said leading edge, said flap articulated to said second end of said support structure at said articulation point, said articulation having an axis of rotation that is both substantially within 45 degrees of horizontal and substantially perpendicular to said direction, said flap being movable substantially in rotation about said axis, said rotation being in a quarter-cylindrical space behind said axis, said space being away from said direction of travel and generally above the horizontal, and (c) a rotation limiting mechanism situated on one of said support structure, said flap or said water craft for preventing the flap from rotating beyond a position substantially parallel to said direction.
In yet another embodiment, the propulsion mechanism comprises (a) a support structure comprising a support element, said element comprising a first dimension, a second dimension, a third dimension, a first end and a second end, said first end comprising an adaptation for attachment to said water craft, (b) a flap comprising a leading edge, a trailing edge, a width between said leading edge and trailing edge and an articulation point located within the first 25% of said width as measured from said leading edge, said flap articulated to said second end of said support structure at said articulation point, said articulation having an axis of rotation that is substantially perpendicular to said direction, said flap being movable substantially in rotation about said axis, said rotation being in a semicylindrical space behind said axis, said space being away from said direction of travel, (c) a rotation limiting mechanism situated on one of said support structure, said flap or said water craft for preventing the flap from rotating beyond a position substantially perpendicular to said direction, and (d) a torque generating mechanism connected between said flap and said support structure, said mechanism comprising a stressed material exerting torque on said flap, said torque directed so as to rotate said flap toward a position substantially perpendicular to said direction, said torque being exerted on said flap at all rotation positions of said flap.
In yet another embodiment, the propulsion mechanism comprises (a) a pivot axis, (b) a pivot support bracket adapted for attachment to said water craft and adapted for supporting said pivot axis, (c) a foot actuated pedal crank comprising a first end connected to said pivot axis, a second end, and a pedal attached to said second end, (d) a support structure comprising a generally elongated bar element, a first end and a second end, said first end attached to said second end of said pedal crank, said attachment forming a predetermined angle between said bar element and said pedal crank, said angle measured in a plane perpendicular to said pivot axis, and (e) a flap comprising a leading edge, a trailing edge, a width between said leading edge and trailing edge and an articulation point located within the first 25% of said width as measured from said leading edge, said flap articulated to said second end of said support structure at said articulation point, said articulation having an axis of rotation that is substantially perpendicular to said direction, said flap being movable substantially in rotation about said axis said rotation being in a semicylindrical space behind said axis, said space being away from said direction of travel. Preferably, said apparatus further comprises a rotation limiting mechanism situated on one of said support structure or said flap for preventing the flap from rotating beyond a position substantially perpendicular to said direction. In another preferred embodiment, said apparatus comprises a torque generating mechanism connected between said flap and said support structure, said mechanism comprising a stressed material exerting torque on said flap, said torque directed so as to rotate said flap toward a position substantially perpendicular to said direction, said torque being exerted on said flap at all rotation positions of said flap. Said flap is preferably buoyant and said axis of rotation is preferably within 45 degrees of horizontal.